Semi-insulating silicon carbide (SI-SiC) substrates, renowned for their high resistivity, wide bandgap, high thermal conductivity, and excellent breakdown electric field, play an irreplaceable role in high-frequency electronics, power electronics, and radiation detection. Among SiC polytypes, 4H-SiC is the mainstream choice due to its superior carrier mobility and outstanding electrical characteristics.

I. RF and Microwave Power Devices

1. GaN-on-SiC High Electron Mobility Transistors (HEMTs)

Semi-insulating SiC substrates enable GaN epitaxy with significantly reduced RF losses and parasitic conduction, resulting in higher power density and efficiency. Research teams at Duke University, Tsinghua University, and Kyoto University are developing high-frequency (X- to Ka-band) GaN-on-SiC power amplifiers for 5G base stations, satellite communications, and advanced radar systems. Compared to GaN-on-Si, these devices offer superior thermal management and reliability, making them a key direction for next-generation RF front-ends.

2. SiC-based MESFETs and JFETs

Devices fabricated on SI-SiC substrates exhibit lower feedback capacitance and higher gain performance. Institutions such as CETC and the National University of Defense Technology in China are promoting domestic millimeter-wave power devices. With the growth of millimeter-wave communications and advanced electronic warfare, RF devices based on SI-SiC substrates will see broader application prospects.

II. Insulating Substrates for Power Electronics

While conductive 4H-SiC is typically used for vertical power devices (e.g., MOSFETs and Schottky diodes), semi-insulating SiC is advantageous as an insulating substrate for high-voltage power modules:

High-voltage isolation: Bulk resistivity exceeding 10^7 Ω·cm ensures module safety.

Superior thermal performance: Thermal conductivity approaching that of copper supports high power-density packaging.

Reduced parasitic effects: Minimizes leakage current and electromagnetic interference during operation.

Teams at North Carolina State University and Zhejiang University are exploring SI-SiC substrates to enhance thermal management and reliability in automotive traction drives and industrial power systems. With the rapid rise of EVs and high-end industrial equipment, these substrates will find increasing use in high-power converters and power modules.
 

Picture1：Semi-Insulating Silicon Carbide Substrates

III. Detectors and Sensors

1. Radiation Detectors

With low dark current and high energy resolution, SI-SiC is widely used in X-ray, gamma-ray, and neutron detectors. CERN (Europe), Peking University (China), and Tomsk Polytechnic University (Russia) are developing SI-SiC-based detectors for high-energy physics and nuclear safety. The exceptional radiation hardness of SI-SiC makes it ideal for nuclear plant monitoring and space exploration missions.

2. High-Temperature and High-Pressure Sensors

Capable of stable operation above 600°C, SI-SiC is used for aerospace engine monitoring, oil and gas exploration, and geothermal probing. NASA Glenn Research Center and Harbin Institute of Technology have jointly validated its long-term reliability under extreme conditions. Future applications include deep-well drilling, rocket engines, and nuclear reactor monitoring.

IV. Optoelectronic and Quantum Devices

Semi-insulating SiC also supports millimeter-wave, terahertz, and integrated optoelectronic circuits, reducing substrate losses and improving system efficiency. In recent years, deep-level defects in 4H-SiC (e.g., V and N defect centers) have been studied as quantum sensors and single-photon sources. Stanford University and Shanghai Jiao Tong University have achieved breakthroughs in quantum communications and quantum metrology, laying the material foundation for next-generation quantum information technologies.

Conclusion

As a core material for high-performance electronic devices, semi-insulating SiC substrates are driving advances in RF, power, detection, and quantum technologies. With the maturation of material growth techniques (e.g., PVT and improved CVD) and defect control methods, SI-SiC will see broader adoption in defense, energy, and information industries. Our company also supplies high-quality silicon carbide substrates to leading universities and research institutions, supporting cutting-edge research and accelerating the development of next-generation high-performance devices.